Assessment the viability properties of Lactobacillus casei strain using labneh as a carrier

Abstract

Background. Our study was conducted in two stages; the first stage was to examine the fructose fermentation profile by Lactobacillus (Lb.) casei FEGY9973. The second stage was to investigate the viability properties of Lb. casei either during cold storage of labneh or under simulated gastrointestinal tract (GIT) conditions. Material and methods. Labneh as a carrier medium was classified into four treatments; the first one con- tained 2% free cells of Lb. casei as a control. The second, third and fourth treatments used 2% of encapsulated cells of Lb. casei with different capsule materials, including alginate-milk, sodium alginate and κ-carrageenan served as T1, T2 and T3 respectively. The physiochemical, microbiological and sensory properties of labneh during 15 days of cold storage were shown. Moreover, the viability of free and encapsulated Lb. casei sub- jected to some manufacturing and simulated GIT conditions was tested.

Results. It was revealed that lactate was the major metabolite in the medium for colonic fermentation, where- as no amounts of ethanol could be detected. Moreover, labneh samples including free cells of Lb. casei had lower pH values than treatments containing microcapsules of Lb. casei. The levels of moisture, acetaldehyde and diacetyle in treatments with different encapsulated materials were increased during the cold storage period. Accordingly, labneh samples with encapsulated Lb. casei had higher sensory scores than the control. In addition, labneh samples with Lb. casei in milk-alginate microcapsules showed a high viability during cold storage and under simulated GIT conditions. A significant decrease in the viability of free or encapsulated Lb. casei was observed at 15 days of cold storage.

Conclusion. Encapsulated Lb. casei by alginate-milk was more resistant during the cold storage period and under simulated gastric conditions than the other two treatments.